JPS5825990B2 - Simultaneous distance and relative velocity measurement device using reflection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a frequency modulated continuous wave radar range and relative velocity measuring device.

This type of device has been patented for example in Germany. No. 867.709.

The device is a frequency modulated continuous wave radar device, referred to as a "pMCW device" in the following description.

In this FM-CW device, the superposition of the signal reflected from the target and the local signal produces a beat signal that is dependent on distance and velocity, from which distance and relative velocity are determined.

The embodiments described in said patents can be divided into two groups:

1. A group that determines distance and relative velocity simultaneously.

2. A group in which measurements of distance and relative velocity are performed sequentially.

In the first case, two transmitter-receivers are required.

To measure distance, a frequency modulated signal in the form of a tooth-tooth wave is emitted from a first transmitter.

To measure relative velocity, unmodulated signals are simultaneously emitted from a second transmitter.

Distance and relative velocity determinations at the receiver are also made simultaneously.

In the second case, only one receiver-receiver is provided.

Only alternating frequency-modulated and non-modulated signals or signals frequency-modulated in the form of a triangular wave are radiated.

The received signals are determined for range and relative velocity either sequentially or simultaneously if suitable storage is available.

If the radiated signal is only frequency modulated in the form of a triangular wave, then
It is not possible to determine the positive or negative polarity of relative velocity.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device for measuring distance and relative velocity simultaneously by the reflection method, with only one transmitter-receiver, such that distance and relative velocity are simultaneously extracted from the same received signal together with the positive and negative polarities of the relative velocity. That's true.

Although only one receiver--receiver is provided, the present invention has the advantage that it is possible to simultaneously determine the beat signal for distance and relative velocity, including the positive and negative polarities of relative velocity.

Storage is no longer required.

To measure distances, the area to be monitored is searched within a very short time.

When a target is detected, a beat signal including frequency components representing distance and relative velocity according to the transmitted wave and the reflected signal is output from the first means including the first mixer.

The output of this first means is input to a second mixer constituting the second means, and a local oscillator that sequentially generates a plurality of preset frequencies is coupled to the second mixer. ing.

In this local oscillator, a plurality of oscillation frequencies are measured so that partial frequency regions corresponding to individual distance ranges obtained by dividing the distance to be measured into a plurality of regions are outputted from the second mixer as frequencies in the same range. These oscillation frequencies are set in advance to correspond to the desired distance ranges, and these oscillation frequencies are sequentially switched to sequentially test each distance range.

The output of this second means is then coupled to third means for producing an output for determining the distance to the target, for example by a third mixer responsive to this output in synchronization with the transmit frequency sweep.

This output has the same frequency range at each distance range,
Depending on the oscillation frequency at which the output was obtained, the distance range from which the reflected signal originates can be specified.

In addition, by setting the frequency range to be the same in this way, the harmonics of the modulated wave that have undergone the same Doppler shift in each distance range can be
Therefore, by providing a fourth means for determining the frequency in response to the output of the third means, the relative velocity can be simultaneously determined.

If time is required to determine the relative speed, the third means interrupts the switching operation of the oscillation frequency of the local oscillator when the output is generated, and continues oscillation at that frequency.

The switching of the oscillation frequency of the local oscillator is restarted again after the required time of the relative speed determining device.

The speed of only one target can be determined, or the speed of several targets can be determined.

The device of the invention is fully operational even when multiple targets are present within the range to be monitored.

The novel device of the invention is particularly suitable for use as a motor vehicle traffic (radar) monitoring device.

The invention will be explained in more detail with reference to the embodiments described below with reference to the accompanying drawings.

First, the operation of a known FM-CW device will be described with reference to FIG.

The signal SA is frequency modulated in the form of a triangular wave (Fig. 1a).
.

Modulation frequency 'mod is 20kHz, frequency deviation Ap is 6
0MHz, carrier frequency f.

Assume that 16.5 GHz is 16.5 GHz. When the emitted signal SA is reflected by a fixed target, the FM-CW device
The signal SE is received.

When the target moves, the FM-CW device sends the first signal SE'
A second signal SE is received having a frequency offset from the frequency of by a Doppler shift f1) due to the moving target.

By mixing the transmitted signal SA with the received signal SE,
A difference frequency fDiff which is proportional to the distance is obtained and its variation over time is shown in FIG. 1b.

The solid line shows the difference frequency fDiff-fR for a fixed target, and the dotted line shows the difference frequency fDiff for a moving target.0 In the case of a moving target, the difference frequency fD for a fixed target
i ff "" fR decreases by the value of the Doppler shift fD during times when the transmit frequency increases, whereas the opening frequency during times when the transmit frequency decreases increases correspondingly.

When the frequencies of the radiated signal and the received signal are equal to each other,
The difference frequency fDi f is O.

When it is O, the beat signal (video signal) shows a phase jump.

The video signal is periodic (period 1 -) and m0d = f
mod, the result is a frequency line proportional to the distance, which has the form (Fig. 1c) and whose envelope maximum point corresponds to the round-trip distance of "transmitter-target-receiver". It becomes a spectrum.

In the case of a fixed target, all frequency lines in the video spectrum will be integer multiples of the modulation frequency, as shown by the thick lines in FIG. 1c.

In contrast, when there is relative movement, Doppler lateral lines (shown as thin lines) occur above and below the stationary echo line (which is absent in this case).

Due to the symmetry of the triangular modulated wave, upper and lower Doppler lateral lines occur regardless of the direction of movement, and therefore it is impossible to distinguish between positive and negative polarities of the Doppler frequency.

In order to determine the positive and negative polarities of such relative velocity, the present invention uses asymmetric frequency modulation.

The difference frequency fDiff (FIG. 1e) is then increased by a constant value, the Doppler frequency fD (when approaching the target), or decreased by a constant value, the Doppler frequency (when moving away from the target).

The echo spectrum produced by the rise time due to the retrace part of the modulated signal having a very short duration (the rising part of the tooth-tooth curve in Figure 1d) increases in frequency by a factor proportional to the anti-fall time. high and therefore separated from the actual useful spectrum.

The frequency spectrum of the video signal is shown in Figure 1f.

Its envelope maximum point is assigned to the distance.

However, since only a lower or upper Doppler side line is produced depending on whether the target is moving away or approaching, the polarity of the relative velocity is determined by a determination device, which will be described later.

When using the FM-CW device according to the invention, the distances from several targets and the relative velocities of those targets can be measured.

However, in many cases, especially in the case of automotive radars, in addition to the distances from all targets, only the relative velocity of the target at the shortest distance from the FM-CW device is of interest.

The FM-CW device is designed according to the requirements, ie whether the relative velocity of one, several or all targets is to be measured.

The following description is exemplary and describes a device that measures only the relative velocity of the target closest to the FM-CW device.

FM of one embodiment of the present invention with reference to FIGS. 2 to 6 below.
-Describe the CW device.

FIG. 2 shows a block diagram of the entire FM-CW device.

The frequency f generated by the oscillator 1.

=16.5 GHz is frequency modulated in the form of a tooth-tooth wave by a tooth-tooth generator 2.

The frequency modulated signal SM is guided to an antenna 5 via a circulator 4 and radiated from this antenna.

The modulation frequency fmod is 20 kHz and the frequency deviation AF is 60 MHz.

Since the desired high measurement accuracy requires high stability of the modulation frequency, the modulation frequency is 1 0 generated by the oscillator 13.
．． It is generated by dividing the frequency of 62 MHz in the frequency divider 14.

In addition to the signal SR received from the antenna 5 being added to the first mixer 6 , a portion of the signal SM taken out from the feed path to the circulator 4 by the directional coupler 3 is added to the first mixer 6 .

By mixing the received signal SR and the extracted signal SM in a mixer 6, a video signal containing information about distance and relative velocity is obtained.

When the distance to be monitored ranges from 10m to 130m, the frequency of the video signal is 1601d (
z and 2080 kHz.

The distance to be monitored is divided into 12 distance ranges, each 10 m long.

Each distance range is assigned one frequency.

In order not to disturb the superposition of the effective signal and the local signal during the retrace time of the tooth-tooth modulated signal, the switch 21 controlled by the one-shot multi-by-break 8 at the repetition rate of the modulation frequency is activated during that time. Prevent the video signal from passing through the amplifier 1.

The time constant of the one-shot multi-by-break 8 is equal to the retrace time of the sharp tooth wave.

The amplified video signal is led to a second mixer 9 where it is converted to a higher frequency by successively different frequencies.

These frequencies are generated in oscillator bank 10, the control operation of which will be described below with reference to FIG.

Each frequency has one distance range (e.g. frequency 9
．． 66 h is assigned to a distance range 60-70 m), ie the number of frequencies is equal to the number of distance ranges.

A steeply sloped bandpass filter 11 having a bandwidth of 160 kHz is connected after the second mixer 9.

The bandwidth corresponds to the length of each distance range. Filter 1
The center frequency of 1 is 10.7 MHz.

Only when the video signal is mixed in the second mixer 9 with a frequency assigned to the distance range in which the specific target is located;
A signal is produced at the output of filter 11.

Therefore, when we know the frequency to mix, we know within what distance range the target is.

In the third mixer 12, the frequency of the filter output signal is converted to a frequency range of 0-160 kHz which facilitates the implementation of circuits for further determining distance and relative velocity.

Therefore, the filter output signal is sent to the third mixer 12 at 10.
It is mixed with a signal at a frequency of 62 MHz.

This signal is generated by the oscillator 13. The mixer output signal is applied to a distance determination circuit 16 and a relative speed determination circuit 17.

First, the distance determination circuit 16 will be explained next with reference to FIG.

The input signal of the distance determination circuit 16 has a passband of 0 to 80kHz.
Low-pass filter 31 with passband 80-160 kHz
A bandpass filter 32 with z and a threshold circuit 38 are added to the subsequent first rectifier 35 .

If the video signal has sufficient amplitude for further distance determination (this depends on the threshold value of threshold circuit 38), threshold circuit 38 produces a distance signal SE.

The output signals of the low-pass filter 31 and the band-pass filter 32 are rectified by rectifiers 33 and 34, respectively, and the output signals of the comparator 36 are
added to one manpower.

When the amplitude of the rectified output signal of the low-pass filter 31 is larger than the amplitude of the rectified output signal of the band-pass filter 32,
produces a binary value of 1 at the output of comparator 36, i.e. signal SF
1 is obtained at the output of the distance determining circuit.

Under the opposite condition, the output of comparator 36 will produce a binary value of zero.

In this case, the inverter 37 produces a binary value of 1 as the distance determination circuit output signal SF2.

The 10 m distance range is now divided into 5 m distance ranges depending on the states of the signals SFI and SF2.

When the amplitude of the output signal of the low-pass filter 31 is greater than or equal to the amplitude of the output signal of the band-pass filter 32, the target is 10
It can be seen that it is within the first half of the m distance range.

Next, the relative speed determination circuit 17 will be explained with reference to FIG.

To determine the Doppler frequency in absolute value and polarity, determinations are made before and after a single spectral line (FIG. 1f) within a frequency range determined by:

n-fmOd-1kH2〈n-fmodζn-fmod
+5kHz2 Therefore, the target has a distance range of 0-160kHz
If the target is at the upper end of the range 160 kHz or the target is at the lower end of the range OHz, the 80 kHz line has sufficient amplitude for further processing, so the distance range 0
-160 kHz center (n-fmOd-80kHz)
Use the line in .

The band limitation is performed by a band pass filter 41 having a pass band of 7985 kHz.

At a frequency of 79 kHz (Doppler deviation of 1 kHz), the target is moving away at approximately 30 km/h.

At a frequency of 85 kHz (Doppler deviation +5 kHz) the target is moving towards the nearer with a relative speed of about 160 km/h.

Between the frequency range 79-85 kHz, the Doppler deviation is 79 kHz to 80 kHz for a moving target that is moving away.
Hz (-30 km/h to Okm/h) and 80 kHz for approaching moving targets.
from 85 kHz (Okm/h to +160 km
/h).

To determine the positive or negative polarity of the relative velocity, a check is made to see if the Doppler frequency is greater or less than 80 kHz.

This will be explained later.

To determine the relative velocity, said frequency range is searched by a tuned filter.

Because we have to rapidly explore the area to be supervised,
Requires a filter with short transient response time.

The transient response time of a filter is inversely proportional to its absolute bandwidth.

Therefore, narrowband search filters have long transient response times.

Therefore, N-path filters are particularly suitable for use as narrowband search filters.

It will be seen that an N-path filter controlled by the clock frequency fTa has several passbands with a spacing given by the clock frequency.

Since there are several passbands, additional signal components pass through and the above relationship between transient response time and absolute bandwidth results in a shortening of the transient response time.

The non-zero center frequency of the first passband is equal to the clock frequency.

However, since the output signal is now clear (with several passbands), a bandpass filter must be connected after the N-path filter.

The passband of this bandpass filter is equal to the tuning range of the N-path filter.

This broadband nature does not significantly change the transient response time of the overall filter system.

The above combination of an N-path filter followed by a bandpass filter results in a narrowband search filter with a short transient response time.

N-path filter 47 consists of three parallel low-pass filters (bandwidth 150 Hz), and the output signal of bandpass filter 41 is applied to the N-path filter via a time division multiplex switch.

The bandwidth of N-path filter 47 is equal to twice the bandwidth of its respective low pass filter.

The time division multiplexing switch of N-path filter 47 is controlled by voltage controlled oscillator (VCO) 52.

The VCO 52 has a frequency range of 7 within 50m5 (20Hz) by a clean tooth wave signal generated by a clean tooth wave generator 53.
It is tuned over 9-85 kHz, ie the time division multiplexing switch of N-path filter 47 is controlled at frequencies from 79 kHz to 85 kHz.

In this way, the N-path filter 47 becomes a search filter for the frequency range from 79 kHz to 851d(z).

For accuracy reasons, VCO 52 operates at a higher frequency than is necessary to control N-path filter 47.

When vCO 52 is tuned over the frequency range 237-255 kHz, the output frequency of VCO 52 for controlling N-path filter 47 must be divided by 1 in frequency divider 51.

Only when the center frequency of N-path filter 47 corresponds to the frequency of the Doppler shift spectral line will a signal be produced at the output of the bandpass filter after N-path filter 47.

When generating a signal at the output of the bandpass filter 48 to determine the relative speed, the relative speed signal processing circuit 19 uses the VCO 5
Measure the oscillating frequency of 2.

The output signal of the bandpass filter 41 is also applied to a threshold circuit 46 after being rectified by a rectifier 45 .

If this signal has a predetermined amplitude, threshold circuit 46 produces signal SDV.

The output signal of the bandpass filter 48 is rectified by a rectifier 49 and applied to a threshold circuit 50.

If this signal has a predetermined amplitude, threshold circuit 50 produces signal SD.

The distance signal processing circuit 18 will now be described with reference to FIG.

The following signals are present at each input of circuit 18.

Signals SFI, SF2...These signals divide the distance range into two distance ranges.

Signal SE: Signal from the distance determination circuit 16.

Signal SDV: Signal from relative speed determination circuit 17.

A 2 kHz clock signal is obtained from a frequency divider 15 that divides the frequency of the oscillator 13.

A 2 kHz clock signal is applied to the non-inverting input of inhibit gate 64 and sent to controller 65.

The control device 65 produces output signals El-E12, the number of which is equal to the number of distance ranges.

The clock signal switches the controller cyclically from one output to the next.

The output signal E1-El2 is the oscillator bank 10 (FIG. 2).
used to control

By this control, each input signal of the second mixer 9 is cyclically mixed with each frequency of the oscillator bank 10 assigned to one distance range at the clock frequency (21d(z)).

Each output signal of the control device 65 is connected to the M(a) gate 66/1-
Added on 66/12.

Signals SDV and SE are applied to AND gate 61.

The output signal of this AND gate controller 1 is the output signal of the AND gate 6.
In addition to being added to 6/'f -66/12, it is also added to flip-flop 62.

A one-shot multi-by-break 63 is connected next to the flip-flop 62.

The time constant of one-shot multi-by-break 63 is 50m.
5, equal to the time required to determine the Doppler shift.

The output signal of one-shot multivibrator 63 is applied to the inverting input of inhibit gate 64.

As long as a signal is present at the inverting input of this inhibit gate 64,
The controller 65 does not switch to the next output.

Searching cannot continue until the one-shot multi-by-break 63 returns to its stable state.

Flip-flop 62 is reset by the last output signal E12 of control device 65.

This ensures that the relative velocity of targets other than the first target is not measured.

When all relative velocities have to be measured,
Flip-flop 62 is not required.

When the relative velocities of several targets have to be measured, several more flip-flops are added and controlled appropriately.

The output signal ST of the flip-flop 62 is also applied to the relative speed signal processing circuit 19.

ANDN-The output signals of gates 66-66/12 are AND
N-Gate 6 Fu-67/12 and 68/1-68/1
Added to 2.

The signal SFI is the second of AND gates 67/1-67/12.
added to the human power, signal SF2 is ANDN-gate 68-
Added to the 2nd manpower of 68/12.

The rough distance is determined by signals E1-E12, and the precise distance is determined by signals SF1 and SF2.
Determined by assigning to.

ANDN - Gate 6 Fu - 67/12 and 68/168
/12 output signals are respectively flip Flora 7'69
．． Set 70.

An indicator lamp 80 of the indicator circuit 20 is connected after the flip-flop 69, 70, and it is known at what distance the target is present when one lamp is ignited.

Each flip-flop 69, 70 is reset after the completion of one switching cycle, ie flip-flop 69/2, which is set only when signal E2 is present, is reset by signal E1.

The relative speed signal processing circuit 19 will now be described with reference to FIG.

The output signal ST of the flip-flop 62 of FIG.

Signal ST controls trigger circuit 71.

Trigger circuit 71 produces a first short pulse at the beginning of signal SD and a second short pulse at the end of signal SD.

The frequency of the signal 5vCO is measured by a frequency meter 73.

The measured frequency values are stored in two registers 72, 74 in binary form.

The value present at the beginning of the signal SD is stored in the first register 72.

The first pulse serves to write to register 72, the second
The pulses serve to write to the second register 74.

Reading of the values stored in registers 72,74 is controlled by read pulse L and cleared by pulse E12 at the end of the switching cycle.

A well-known average calculator 75 averages the two frequency values stored in the register.

Such an averaging function is performed, for example, by adding the stored value to 72.74 and dividing by two.

The output signal of the average calculator 75 is decoded by a decoder 77 and displayed as a relative velocity on a digital indicator 81 of the indicator circuit 20, or converted from digital to analog by a DA converter 79 and displayed as an analog indicator. 82.

Comparator 78 compares the binary output signal of average calculator 75 with a frequency corresponding to a Doppler shift of "0".

The reference frequency is entered into the calculator in the form of a binary word.

When the measurement frequency is higher than the reference frequency, the target is FM
- The target is moving toward the CW device, and when the measurement frequency is lower than the reference frequency, the target is moving away from the CW device.

The positive and negative polarity values are also sent to the indicating circuit 20 and displayed there.

As can be seen from the given measurement range, the above-mentioned radar device is intended to be installed inside a car, and the measured values can be used to prevent a collision.

This is especially the case if an additional computer is provided which takes into account various parameters and only generates a signal when a collision is imminent.

[Brief explanation of the drawing]

Figure 1 shows waveforms (
Figures 1a-1c) and waveforms for explaining the FM-CW device according to the present invention (Figures 1d1f), Figure 2 is a block diagram of the FM-CW device according to the present invention, and Figure 3 is the distance of Figure 2. Figure 4 is a block diagram of the relative speed determination circuit in Figure 2. Figure 5 is a block diagram of the distance signal processing circuit in Figure 2. Figure 6 is the relative velocity signal processing circuit in Figure 2. It is a block diagram of a circuit. 1... Oscillator, 2... Fine tooth wave generator, 3... Directional coupler, 4... Circulator, 5...・Antenna, 6...
First mixer, 7...Amplifier, 8...One-shot multi-by-break, 9...Second mixer, 10...Oscillator bank, 11...・・・・・・
・Band pass filter, 12...Third mixer, 1
3... Oscillator, 14... Frequency divider, 15
... Frequency divider, 16... Distance judgment circuit,
17... Relative speed determination circuit, 18...
Distance signal processing circuit, 19... Relative speed signal processing circuit, 20... Indication circuit, 21... Switch, 31... Low pass filter, 32... ...
・Band pass filter, 33, 34.35...
Rectifier, 36... Comparator, 37... Inverter, 38... Threshold circuit, 41...
... Bandpass filter, 45 ... Rectifier,
46...Threshold circuit, 47...
・N-path filter, 48... Bandpass filter, 49... Rectifier, 50... Threshold circuit, 51... Frequency divider, 52...・・・
... Voltage controlled oscillator, 53... Fine tooth wave generator, 61... AND gate, 62...
Flip-flop, 63 one-shot multi-by-break, 64...inhibition gate, 65-...control device, 66/1-66/12...AND gate, 67/1- 67/12, 68/1-68/12
...AND gate, 69/1-69/12
. 70/1-70/12...Flip-flop,
80... Indication lamp, 71... Trigger circuit, 72, 74... Register, 73...
...Frequency meter, 75...Average calculator, 77...
...Decoder, 18...Comparator, 79...
...D-A converter, 81...Digital indicating instrument, 82... Analog indicating instrument.

Claims (1)

[Claims] 1. A frequency sweep device for transmitting a frequency-modulated high frequency wave and receiving a reflected signal from at least one other moving body, which is mounted on the moving body and connected to the other moving body. in a frequency modulated continuous wave device for measuring distance and relative velocity over a predetermined range, a first mixer generating a beat signal output containing frequency components representing distance and relative velocity in response to the transmitted wave and the reflected signal; a second mixer that operates in response to the beat signal output of the first means;
a local oscillator that sequentially generates a plurality of predetermined frequencies connected to a mixer of the frequency modulated radio frequency; second means comprising means for sequentially setting a plurality of frequencies on said local oscillator to generate a mixer output of; an output for determining a distance between said mobile object and said other mobile object; third means comprising means synchronized to said frequency sweep device and responsive to the output of said second mixer to generate: during the time of the signal determining the distance from said third means; To generate a signal that determines its corresponding relative velocity,
and fourth means for generating a signal frequency determination output for determining the current relative velocity of the output of the third means in response to the distance determining output of at least the third means. A frequency modulated continuous wave distance and relative velocity measuring device featuring: 2. Claim 1 comprising a device for performing frequency modulation according to a sharp tooth waveform having a slope portion and a retrace portion such that the transmit frequency is changed substantially linearly during the period of the slope portion. The device described. 3. A patent claim comprising means for interrupting the oscillation frequency switching operation of the local oscillator so that a signal for determining the relative velocity by the fourth means can be simultaneously generated at a frequency corresponding to the distance of the target. range 1
Apparatus described in section. 4. comprising a bandpass filter for extracting the partial frequency spectrum in response to the output signal of the second means, the passband of the filter corresponding to a predetermined one of the distance ranges;
2. The apparatus of claim 1 further comprising a third mixer responsive to said partial frequency spectral signal for converting said spectral signal to a lower frequency range for range and Doppler determination and display. 5. During the retrace portion of the frequency modulated sharp tooth wave, the first
3. Apparatus according to claim 2, further comprising means for preventing the output of the mixer from occurring. 6 first and second bandpass filters that respond to the output signal of the third mixer and divide the passband produced at the output of the third mixer into first and second parts; and the partial frequency spectrum. means for generating first and second control signals indicative of whether a signal is present in the first or second portion; 5. The apparatus of claim 4, further comprising a distance determination circuit including means for generating a control signal of 4. 1. A third band pass filter that filters and passes a frequency range corresponding to the Doppler shift predicted from the output signal of the third mixer, and the output signal of the band pass filter has a predetermined amplitude or more. a relative velocity determination circuit including means configured to generate a fifth control signal to be sent to the distance signal processing circuit when the output signal of the tuned filter controlled by the voltage controlled oscillator is greater than or equal to a predetermined amplitude; determining a Doppler shift using the tuned filter so as to send a sixth control signal to the relative speed signal processing circuit when the voltage controlled oscillator reaches the relative speed signal processing circuit; An apparatus according to claim 5, which is constructed as follows. 8. The device of claim 7, wherein the tuned filter is configured as an N-path filter. 9. Device according to claim 8, characterized in that a bandpass filter having a passband equal to its tuning range is connected after the 9 N-path filter. 10. The apparatus of claim 7, wherein the frequency range filtered by the third bandpass filter is close to the frequency assigned to the center of a given partial distance range. 11 The distance signal processing circuit includes a control device that generates an output signal that cyclically switches the frequency to be mixed into the received signal in the second mixer, and outputs the signal to the second AND gate in response to the fourth and fifth control signals. , a second AND gate having an input responsive to the control device, and a flip-flop circuit controlled by the second AND gate to control each instruction circuit. The device according to item 7. 12 an additional AND gate and an additional flip-flop for dividing the distance range into partial distance ranges, said second control signal being applied to one of the inputs of the first part of said additional AND gate, and said third control signal is said addition AND
12. The apparatus of claim 11, wherein the output of the second AND gate is coupled to the other input of the additional AND gate. 13. The apparatus of claim 11, wherein an additional circuit is interposed between the first AND gate and the control device to prevent the control device from switching to the next output during speed determination. 13. The device of claim 12, wherein a further circuit for determining the target for which the speed is to be determined is interposed between the additional circuit and the first AND gate. 15 To determine the relative speed, the relative speed signal processing circuit measures the frequency of the voltage controlled oscillator when said sixth control signal is present, and then sends the speed value to the indicating circuit to determine the positive or negative polarity of the relative speed. 8. Apparatus as claimed in claim 7, including means for comparing the frequency of the voltage controlled oscillator with a frequency corresponding to a relative velocity of "0".